Dose Setting Mechanism or Priming a Drug Delivery Device

ABSTRACT

A method and system for priming a drug delivery device. The drug delivery device includes a dose dial sleeve and an internal housing portion. The dose dial sleeve is coupled to the internal housing. The dose dial sleeve rotates on a substantially circumferential rotational path during priming of the drug delivery device. Further, the dose dial sleeve rotates on a helical path during dose setting of the drug delivery device.

FIELD OF THE PRESENT PATENT APPLICATION

The present patent application is generally directed to drug deliverydevices. More particularly, the present patent application is generallydirected to drug delivery devices, such as pen type drug deliverydevices. Such devices provide for self administration of medicinalproduct from a multi-dose cartridge and permit a user to set thedelivery dose. The present application may find application in bothresettable (i.e., reusable) and non-resettable (i.e., non-reusable) typedrug delivery devices. However, aspects of the invention may be equallyapplicable in other scenarios as well.

BACKGROUND

Pen type drug delivery devices have application where regular injectionby persons without formal medical training occurs. This is increasinglycommon among patients having diabetes where self-treatment enables suchpatients to conduct effective management of their disease.

In certain types of medication delivery devices, such as pen typedevices, cartridges of medication are used. These cartridges are housedin a cartridge holder or cartridge housing. Such cartridges include abung or stopper at one end. At the other end of the cartridge, thecartridge comprises a pierceable seal. To dispense a dose of medicationfrom such a cartridge, the medication delivery device has a dose settingmechanism that uses a spindle to move in a distal direction towards thecartridge and to press a distal end of the spindle against the bung.This expels a certain set dose of medication from the cartridge. Inorder to insure dose accuracy, it is important that the distal end ofthe spindle remains on the bung of the cartridge before, during andafter injection of a dose of medicament.

One perceived disadvantage of certain known medication delivery devicesis that because of the various tolerance differences that may occurduring manufacturing (e.g., tolerance differences that may arise duringcomponent molding) of the various parts making up the drug deliverydevice and the desire to not pre-load the bung axially in the assembleddevice, there may be a gap between the end of the spindle and thecartridge bung when the medication delivery device is assembled. Inother words, when initially assembled, the cartridge (and hencecartridge bung) may not be in contact with the distal end of thespindle. Therefore, if a user using the drug delivery device for thefirst time dials a dose, the actual dose received may be equal to thedialed dose less the initial gap between the distal end of the spindleand cartridge bung. The air gap between the cartridge bung and distalend of the spindle may be equivalent to a dose that causes the receiveddose that is outside preferred dose accuracy limits. For example, thisair gap may be equivalent to the loss of between 0 and 10 units (i.e.,0-0.14 milliliters) of drug product on the first dose.

There is, therefore, a general need to take these perceived issues intoconsideration when designing either resettable or non-resettable drugdelivery devices, such as pen type drug delivery devices.

SUMMARY

According to an exemplary arrangement, a dose setting mechanism for adrug delivery device is provided. The drug delivery device includes adose dial sleeve and an internal housing portion. The dose dial sleeveis coupled to the internal housing. In this exemplary arrangement, thedose dial sleeve rotates on a circumferential rotational path duringpriming of the drug delivery device. Further, the dose dial sleeverotates on a helical path during dose setting of the drug deliverydevice.

According to another arrangement, a method of priming a drug deliverydevice is provided. The method includes providing a dose dial sleeveengaged with an inner housing of a drug delivery device. The method alsoincludes rotating the dose dial sleeve on a circumferential rotationalpath around the inner housing. In this exemplary arrangement, rotatingthe dose dial sleeve primes the drug delivery device.

These as well as other advantages of various aspects of the presentinvention will become apparent to those of ordinary skill in the art byreading the following detailed description, with appropriate referenceto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are described herein with reference to thedrawings, in which:

FIG. 1 illustrates an arrangement of the drug delivery device inaccordance with the one aspect of the present invention;

FIG. 2 illustrates the drug delivery device of FIG. 1 with a cap removedand showing a cartridge holder;

FIG. 3 illustrates a cross section view of an exemplary dose settingmechanism, such as the dose setting mechanism illustrated in FIG. 2;

FIG. 4 illustrates a perspective view of an inner housing portion of adose setting mechanism, such as the dose setting mechanism of FIG. 3;

FIG. 5 illustrates a perspective view of a dose dial sleeve of a dosesetting mechanism, such as the dose setting mechanism of FIG. 3;

FIG. 6 illustrates a perspective view of the dose dial sleeve coupled tothe inner housing before priming of a dose setting mechanism, such asthe dose setting mechanism illustrated in FIG. 3;

FIG. 7 illustrates a perspective view of the dose dial sleeve coupled tothe inner housing after priming of a dose setting mechanism, such as thedose setting mechanism illustrated in FIG. 3; and

FIG. 8 illustrates a perspective view of the dose dial sleeve coupled tothe inner housing during dose setting of a dose setting mechanism, suchas the dose setting mechanism illustrated in FIG. 3.

DETAILED DESCRIPTION

Referring to FIG. 1, there is shown a drug delivery device 1 inaccordance with an exemplary arrangement. The drug delivery device 1comprises a housing having a first cartridge retaining part 2, and adose setting mechanism 4. The drug delivery device may be a resettabledrug delivery device (i.e., a reusable device) or alternatively anon-resettable drug delivery device (i.e., a non-reusable device). Afirst end of the cartridge retaining part 2 and a second end of the dosesetting mechanism 4 are secured together by connecting features. Fornon-resettable devices, these connecting features would be permanent andnon-reversible. For resettable devices, these connecting features wouldbe releasable.

In this illustrated arrangement, the cartridge housing 2 is securedwithin the second end of the dose setting mechanism 4. A removable cap 3is releasably retained over a second end or distal end of a cartridgeretaining part or cartridge housing. The dose setting mechanism 4comprises a dose dial grip 12 and a window or lens 14. A dose scalearrangement 16 is viewable through the window or lens 14. To set a doseof medication contained within the drug delivery device 1, a userrotates the dose dial grip 12 such that a dialed dose will becomeviewable in the window or lens 14 by way of the dose scale arrangement16.

FIG. 2 illustrates the medical delivery device 1 of FIG. 1 with thecover 3 removed from a distal end 19 of the medical delivery device 1.This removal exposes the cartridge housing 6. As illustrated, acartridge 25 from which a number of doses of a medicinal product may bedispensed, is provided in the cartridge housing 6.

Preferably, the cartridge 25 contains a type of medicament that can beadministered relatively often, such as once or more times a day. Onesuch medicament is either long acting or short acting insulin or aninsulin analog. The cartridge 25 comprises a bung or stopper (notillustrated in FIG. 2) that is retained near a second end or a proximalend 33 of the cartridge 25. The medical delivery device also comprises adriver having a spindle (not illustrated in FIG. 2). As discussed above,before the device is primed, there may or may not be a gap between theend of the spindle and the cartridge bung.

The cartridge housing 6 has a distal end 23 and a proximal end 27.Preferably, the cartridge distal end 23 of the cartridge housing 6comprises a groove 8 for attaching a removable needle assembly. However,other needle assembly connection mechanisms could also be used. If thedrug delivery device 1 comprises a resettable device, the cartridgeproximal end 27 is removably connected to the dose setting mechanism 4.In one preferred embodiment, cartridge housing proximal end 27 isremovably connected to the dose setting mechanism 4 via a bayonetconnection. However, as those of ordinary skill in the art willrecognize, other types of removable connection methods such as threads,partial threads, ramps and detents, snap locks, snap fits, and luerlocks may also be used.

As previously mentioned, the dose setting mechanism 4 of the drugdelivery device illustrated in FIG. 2 may be utilized as a reusable drugdelivery device. (i.e., a drug delivery device that can be reset) Wherethe drug delivery device 1 comprises a reusable drug delivery device,the cartridge 25 is removable from the cartridge housing 6. Thecartridge 25 may be removed from the device 1 without destroying thedevice 1 by merely having the user disconnect the dose setting mechanism4 from the cartridge housing 6.

In use, once the cap 3 is removed, a user can attach a suitable needleassembly to the groove 8 provided at the distal end 23 of the cartridgehousing 6. Such needle assembly may be, for example, screwed onto adistal end 23 of the housing 6 or alternatively may be snapped onto thisdistal end 23. After use, the replaceable cap 3 may be used to re-coverthe cartridge housing 6. Preferably, the outer dimensions of thereplaceable cap 3 are similar or identical to the outer dimensions ofthe dose setting mechanism 4 so as to provide an impression of a unitarywhole when the replaceable cap 3 is in position covering the cartridgehousing 6 when the device is not in use.

FIG. 3 illustrates a cross sectional view of a first arrangement of adisposable dose setting mechanism 50, such as the dose setting mechanism4 illustrated in FIG. 2. With reference to FIG. 3, the dose settingmechanism 50 comprises a dose dial grip 52, a spring 51, an outerhousing 54, a clutch 55, a driver 53, a dial sleeve 56, a spindle 64 andan inner housing 58. In normal use, the operation of the dose settingmechanism 50 occurs as follows. To dial a dose, a user rotates the dosedial grip 52. The driver 53, the clutch 55 and the dial sleeve 56 rotatealong with the dose dial grip. The dial sleeve 56 extends in a proximaldirection away from the inner housing 58. In this manner, the driver 53climbs the spindle 64. At the limit of travel, a radial stop on the dialsleeve 56 engages either a first stop or a second stop provided on theouter housing 54 to prevent further movement. Rotation of the spindle isprevented due to the opposing directions of the overhauled and driventhreads on the spindle. A dose limiter 68, keyed to the outer housing54, is advanced along the thread by the rotation of the driver 53.

When a desired dose has been dialed, the user may then dispense thedesired dose of by depressing the dial grip 52. As the user depressesthe dial grip 52, this displaces the clutch 55 axially with respect tothe dial sleeve 56, causing the clutch 55 to disengage. However theclutch 55 remains keyed in rotation to the driver 53.

The driver 53 is prevented from rotating with respect to the outerhousing 54 but it is free to move axially with respect thereto. Thelongitudinal axial movement of the driver 53 causes the spindle torotate and thereby to advance the piston in a cartridge.

In accordance with an exemplary arrangement, it may be beneficial toforce a user to prime the drug delivery device of FIGS. 1 and 2 beforethe user dials and injects the first dose. In order to achieve thisforced priming, as will be discussed in greater detail below, the dosesetting mechanism 4 of drug delivery device 1 preferably forces a userto prime the device before setting the first dose.

As described above, the dose setting mechanism 50 comprises an innerhousing 58 and a dial sleeve 56 that interact with one another to forcea user to prime the device before dialing a first dose. FIG. 4illustrates one arrangement of an inner housing 70, such as the innerhousing 58 of the dose setting mechanism 50 illustrated in FIG. 3. Theinner housing 70 comprises a threaded portion 72. The threaded portion72 includes a rotational threaded portion 74 and a helical threadedportion 76. The rotational threaded portion 74 may be defined byopposing faces 78 and 80. The rotational threaded portion defines arotational path and the helical threaded portion defines a helical path.As will be discussed in more detail below, movement along the rotationalpath operates to prime the drug delivery device such that the spindle 64(as illustrated in FIG. 3) is moved to an abutting position to a bung ofa cartridge. In addition, movement along the helical path operates toset a dose of the dose setting mechanism (such as illustrated in FIG.3).

The inner housing 70 further comprises at least one non-return element82. The non-return element 82 may be a protrusion from the inner housing70 and the protrusion may be various shapes. For instance, thenon-return element 82 may be a raised substantially rectangular-shapedprotrusion. It should be understood, however, the non-return element 82could be a different shape. In an exemplary arrangement, the innerhousing 70 also includes two non-return elements. However, the innerhousing 70 may have any number of non-return elements. The non-returnelements may be located at the distal end of the inner housing 70 oranywhere along its length.

FIG. 5 illustrates an arrangement of a dial sleeve 84, such as the dialsleeve 56 illustrated in FIG. 3. When assembled, the dial sleeve 84 isplaced over the inner housing 70 and engages with the inner housing 70.As mentioned above, the dial sleeve 84 may be provided with a scalearrangement 16. The dial sleeve 84 also comprises a thread portion 86.This thread portion 86 is preferably an internal thread portion, asdepicted. The internal thread portion 86 is capable of engaging with thethreaded portion 72 of the inner housing 70. In particular, the internalthread portion is capable of engaging with both rotational threadedportion 74 and helical threaded portion 76.

The dial sleeve 84 further comprises at least one non-return element 88.In the exemplary arrangement, the non-return element 82 on the innerhousing 70 is complimentary to the non-return element 88 on the dialsleeve 84. The non-return element may be a protrusion from the dose dialsleeve. In an exemplary arrangement, the non-return element 88 isconnected to a flexible element 90 of the dial sleeve 84. As depicted,the flexible element 90 may be created by a slit in the dial sleeve 84.It should be understood, however, that the flexible element may beformed in different ways. For example, the dose dial sleeve may bemanufactured from flexible material. As will be described in greaterdetail below, this flexible element 90 preferably allows for thenon-return element 88 to pass over the complimentary non-return element82 of the inner housing 70 when the dial sleeve travels through therotational path defined by the rotational threaded portion.

When the dose dial sleeve 84 and inner housing 70 are engaged, theseelements operate as a dose setting mechanism that forces a user to primethe device before a user can set a first dose. In particular, the dialsleeve 84 must travel on a path along the rotational threaded portion 74before the dial sleeve can travel along the helical threaded portion 76.As this dose setting mechanism forces a user to prime the device, thedose setting mechanism described does not suffer from the drawback ofpossibly dispensing an incorrect dose due to the initial separationbetween the spindle 64 and the cartridge bung.

The operation of the dose setting mechanism will be further describedwith reference to FIGS. 6-8. FIG. 6 illustrates a dose setting mechanismbefore priming of the drug delivery device. As depicted, internal thread86 of dial sleeve 84 is engaged with rotational threaded portion 74 ofinner housing 70. A user must first rotate the dial sleeve 84 along apath that is substantially rotational. During the rotational movement,the dial sleeve rotates along a circumferential or circular path. Themovement is limited to movement that is substantially rotational and thedial sleeve does not move axially across the inner housing 70 (i.e., thedial sleeve does not translate).

This circumferential rotational movement acts to prime the drug deliverydevice. As illustrated in the exemplary dose setting mechanismillustrated in FIG. 3, the drug delivery device 1 (or, moreparticularly, the dose setting mechanism 50) may comprise a driver 53and a spindle 64. The dose dial sleeve 84 may be coupled to the driver.Further, as described with reference to FIG. 1, the drug delivery devicemay comprise a cartridge housing which houses a cartridge from which anumber of doses of a medicinal product may be dispensed. This cartridgehousing may be coupled to the dose setting mechanism 50. The movement ofthe dose dial sleeve 84 along the rotational threaded portion may alsocause the driver to rotate. This rotation of the driver may cause thespindle to advance towards the cartridge in the cartridge housing. Thisadvancement of the spindle removes any potential initial separationbetween the spindle and the cartridge bung. In other words, thisadvancement of the spindle caused by the rotation of the dose dialsleeve and driver primes the drug delivery device. Although theexemplary dose setting mechanism 50, as illustrated, is a disposabledose setting mechanism, one of skill in the art will recognize that suchdose setting mechanism may be modified so as to be used as a reusable orresettable dose setting mechanism.

If a user attaches a needle to the drug delivery device 1 before theuser primes the device, then a small amount of drug may be expelledduring the priming operation. Alternatively, if the user attaches theneedle after priming the device or after setting the first dose, thenthe drug, which will be pressurized from the priming, will be expelledas the needle is connected to the drug delivery device. Accordingly, thedrug amount resulting from the priming operation will be expelled beforethe needle is inserted into a user's skin.

FIG. 7 illustrates the dose setting mechanism after priming of the drugdelivery device has occurred. As shown, the rotational threaded portion74 of the inner housing 70 defines a substantially rotational path thatends when the internal thread 86 on the dose dial sleeve makes contactwith the start of the helical thread 76 on the inner housing. When thedose dial sleeve reaches the end of the rotational path or substantiallythe end of the rotational path, the non-return element 82 of the innerhousing and the non-return element 88 of the dial sleeve interact toprevent substantial movement back along the rotational path towards theoriginal start positon. In particular, the non-return element 88prevents the dose dial sleeve from rotating back past the non-returnelement 82. In other words, the non-return elements interact to preventmovement along the portion of the rotational path the dose dial sleevetraveled during the priming of the drug delivery device.

As can be seen by comparing FIGS. 6 and 7, during the priming operation(i.e., the rotational movement of the dial sleeve), the non-returnelement 88 of the dial sleeve is able to travel over the non-returnelement 82 of the inner housing. In addition, the flexible element 90 ofthe dial sleeve allows the non-return element 88 to pass over thenon-return element 90. However, at the end of the rotational path andafter the non-return elements pass one another, the flexible elementsnaps down towards the inner housing, as depicted in FIG. 7. When theflexible element snaps down, the non-return elements 82 and 88 abut oneanother and prevent the dose dial sleeve from going back on therotational path it traveled during the priming of the device. Afterpriming, if a user of the device attempted to move the dose dial sleeveon the rotational path, the movement would be prevented because thenon-return element 88 on the dose dial sleeve will not overcome thenon-return element 82 on the inner housing.

FIG. 8 illustrates the dose setting mechanism during dose setting of thedrug delivery device. FIG. 8 depicts the dose setting mechanism whereapproximately two units have been dialed. As can be seen, when a dose isbeing dialed, the internal thread 86 of the dial sleeve engages with thehelical threaded portion 76 of the inner housing. The drug deliverydevice is designed such that during dose setting, the dose dial sleevetravels on a helical path defined by the helical threaded portion. Thedose dial sleeve cannot engage this helical thread until the dose dialsleeve has been rotated along the rotational thread of the innerhousing. Accordingly, a user cannot dial a first dose until the user hasprimed the device.

In an exemplary arrangement, the drug delivery device may be designed toindicate to a user whether the device needs to be primed or does notneed to be primed before dialing a dose. For instance, dose dial sleeve84 may comprise a graphic printed on it that is displayed in the dosewindow before the pen is primed. The graphic may display a charactersuch as “P” or a phrase such as “Priming Needed.” Other graphics arepossible as well. Once a device has been primed, the graphic will nolonger be displayed in the dose window.

Further, since the non-return elements prevent the dose dial sleeve fromreturning back on the rotational path after priming, the user does nothave to prime the device prior to a subsequent dose. Accordingly, a dosesetting mechanism in accordance with an exemplary embodiment forces auser to prime the device before the first dose is dialed, but does notforce the user to prime the device for subsequent doses.

However, in the event that the drug delivery device is reusable, itshould be understood that a dose setting mechanism in accordance with anexemplary embodiment is designed so that the dose setting mechanismforces a user to prime the device each time a cartridge is replaced. Insuch a reusable device, the device is preferably designed so that a usercould overcome the non-return elements. This may be accomplished, forexample, by rotating the dose dial sleeve over a detent in the dialedposition. This rotation would rotate the number sleeve back along therotational path. Other ways for overcoming the non-return elements arepossible as well.

Further, in this exemplary embodiment, it may be advantageous to forcethe user to do this before being able to remove the cartridge holder.

Exemplary embodiments of the present invention have been described.Those skilled in the art will understand, however, that changes andmodifications may be made to these embodiments without departing fromthe true scope and spirit of the present invention, which is defined bythe claims.

1. A method of priming a delivery device, the method comprising thesteps of: engaging a dose dial sleeve with an inner housing of adelivery device; rotating the dose dial sleeve on a substantiallycircumferential rotational path around the inner housing, whereinrotating the dose dial sleeve primes the delivery device.
 2. The methodof claim 1, further comprising: responsive to the priming of the drugdelivery device, preventing the dose dial sleeve from rotatingcircumferentially.
 3. The method of claim 2, wherein preventing the dosedial sleeve from rotating circumferentially comprises the step ofproviding at least one non-return feature on the dose dial sleeve thatinteracts with at least one corresponding non-return feature on theinner housing.
 4. The method of claim 3, further comprising the stepsof: providing a substantially circumferential rotational thread on theinner housing, and rotating the dose dial sleeve on a substantiallycircumferential rotational path around the inner housing comprisesrotating the dose dial sleeve along the substantially circumferentialrotational thread.
 5. The method of claim 1 further comprising the stepof translating the dose dial sleeve along a helical path during dosesetting of the delivery device.
 6. The method of claim 1, furthercomprising the step of providing an internal housing threaded portion.7. The method of claim 6, wherein the threaded portion comprises arotational threaded portion and a helical threaded portion.
 8. Theinvention of claim 7, further comprising the step of rotating the dosedial sleeve on the rotational threaded portion during priming of thedrug delivery device,
 9. The invention of claim 8, further comprisingthe step of translating the dial sleeve along the helical threadedportion during dose setting of the drug delivery device.
 10. Theinvention of claim 7, further comprising the step of preventing the dosedial sleeve from rotating on the helical threaded portion prior to apriming of the delivery device.
 11. The invention of claim 1, furthercomprising the step of disposing at least one non-return element on thedose dial sleeve.
 12. The invention of claim 11, further comprising thestep of disposing at least one complimentary non-return element on theinternal housing portion that is complimentary to the at least onenon-return element disposed on the dose dial sleeve.
 13. The inventionof claim 11, wherein a substantially rotational path comprises an end ofthe rotational path, wherein, when the dose dial sleeve substantiallyreaches the end of the rotational path, the at least one non-returnelement and the at least one complimentary non-return element interactto prevent substantial movement of the dial sleeve back along therotational path.
 14. The invention of claim 12, wherein the non-returnelement comprises at least one protrusion from the dial sleeve, andwherein the complimentary non-return element comprises at least oneprotrusion from the internal housing.
 15. The invention of claim 14,wherein the non return element is connected to a flexible elementportion of the dial sleeve, wherein the flexible element allows for thenon-return element to pass over the complimentary non-return elementduring the rotational movement, and wherein, at the end of asubstantially rotational path, the flexible element operates to preventthe non-return element to pass back over the complimentary non-returnelement.
 16. The invention of claim 1, further comprising the step ofcoupling the dose setting mechanism and a cartridge housing.
 17. Theinvention of claim 16, further comprising the step of non-reversiblycoupling the dose setting mechanism and the cartridge housing.
 18. Theinvention of claim 1, further comprising the step of providing a graphicon the dose dial sleeve, the graphic being displayed prior to thepriming of the delivery device, wherein the graphic indicates that thedelivery device has not been primed.
 19. The invention of claim 1,wherein the dose setting mechanism further comprises: a driver; and aspindle, wherein the dial sleeve is operatively coupled to the driver,such that rotation of the dial sleeve causes the driver to rotate andthe spindle to translate in a distal direction, this translation primingthe drug delivery device.
 20. The invention of claim 1, furthercomprising: at least one non-return element disposed on the dose dialsleeve; at least one complimentary non-return element disposed on theinternal housing portion that is complimentary to the at least onenon-return element disposed on the dose dial sleeve, wherein, when auser is setting a dose, the non-return element and complimentarynon-return element prevent substantial rotational movement along thesubstantially circumferential rotational path, and wherein, when theuser is not setting a dose, the non-return element and complimentarynon-return element are capable of being overcome by a user of thedevice.